1. Field of the Invention
The present invention relates to a portable terminal including digital communication devices such as a cellular phone, Personal Digital Assistants (PDA), a hand held phone, a camera phone, a game phone, an internet phone, etc., and more particularly to an antenna device for a portable terminal of which transmitting and receiving sensitivity can be controlled as the antenna device is moved slidably on the portable terminal.
2. Description of the Related Art
In general, “a portable terminal” means an electronic device which a user can carry while communicating with another user in radio. In consideration of portability, design of such a portable terminal has been directed not only toward compactness, slimness and lightness, but also toward providing multimedia capabilities to allow the user to pursue a variety of functions. In particular, future portable terminals will be not only used for many functions and purposes despite compactness and lightness, but also be modified to be suitable for functioning in a multimedia environment and for providing internet access and functions. Additionally, such portable terminals may be used by men and women, young and old, anywhere in the world.
Conventional portable terminals may be classified into various types according to their appearance, such as bar-type portable terminals, flip-type portable terminals, and folder-type portable terminals. The bar-type portable terminal has a single housing shaped like a bar. The flip-type portable terminal has a flip which is pivotably mounted to a bar-shaped housing by a hinge unit. The folder-type portable terminal has a folder coupled to a single bar-shaped housing by a hinge unit in such a manner that the folder can be rotated in order to be folded to or unfolded from the housing.
Further, portable terminals may be classified as neck wearable type terminals and wrist wearable type terminals, according to the position at or the way in which a user puts on the terminal. The neck wearable type terminal is one which a user wears around the neck using a lanyard or cord, while the wrist wearable type terminal is one which a user wears around the wrist.
Additionally, portable terminals may be classified as rotation-type terminals and sliding-type terminals according to ways of opening and closing the terminals. In the rotation-type portable terminal, two housings are coupled to each other in a manner that one housing rotates to be opened or closed relative to the other while facing each other. In the sliding-type portable terminal, two housings are coupled to each other in a manner that one housing slides to be opened or closed relative to the other. The various classifications of portable terminals are easily understood by those skilled in the art.
Further, each of the conventional portable terminals enumerated above has been converted so as to allow voice communication, as well as a high-speed data communication. That is, as consumer demands have increased, various services have been provided using wireless communication technology for transmitting and receiving data at a high speed.
It is a present tendency that a camera lens is mounted to the portable terminal, and that it is possible to transmit image signals and the like. Present portable terminals may be provided with an embedded or external camera lens module. Therefore, it is possible to perform image communication with a desired partner or to photograph a desired subject.
On the other hand, the conventional portable terminals commonly have an antenna device, in order to secure a high transmitting and receiving rate and a good signal quality. Conventionally, such an antenna device of a portable terminal has an extendible and retractable antenna such as a helical antenna and a rod type antenna. However, the above-mentioned portable terminal causes the user inconvenience because the rod antenna must be extended or retracted from the terminal whenever radio reception is decreased. Also, it is inconvenient to the user to hold the portable terminal in user's pocket due to the protruding antenna, resulting in diminished portability of the portable terminal. In particular, there is a problem in that the portable terminal may often be broken if dropped.
In the case where the conventional portable terminal has an internal antenna which is fixed inside a body of the portable terminal, it is convenient for a user to carry the portable terminal. However, the portable terminal has a disadvantage in that the radio reception of the internal antenna is deteriorated under poor radio wave environments due to terrestrial interference and other environmental factors.